A Study On Atomization Slope Stability In Yagen Two Cascade Hydropower Station On Yalong River

Yagen two cascade hydropower station is located in the main stream of theYalong river, Which is the third cascade hydropower stations in the middle reaches.Geological Survey exposing that expose atomization zone of slope rock mass stronglyunloading and slacking during feasibility study stage. The right bank along thedirection of slope surface flat structure developmented,colluvial deposit of gravel soilare widely distributed, there are serious problems of slope. Study its stability underthe condition of flood discharge atomization, has important practical significance toensure the safety construction and operation of hydropower station.In this paper, based on identifying the atomization slope geological conditions,deformation and failure features, analysis deformation and failure mode, using thelimit equilibrium method to analyze the stability of natural slope in different operatingconditions; Based on the prediction of release flood waters distribution and energydissipation atomizing rainfall intensity during atomizing, study the change law ofgroundwater seepage and stress field. Using the limit equilibrium method andnumerical simulation to combine the slope stability during atomizing, Researchachievements are as follows.(1) In the study area developed trend NE to pour SE steep grade III structure,trend NWW、NEE grade IV structure、trend NWW grade V structure as the mainfeatures. Controlled by topography and rock structure, slope surface weathering andunloading strongly, the weathering and unloading strength gradually decreased withthe depth, meanwhile the right weathering unloading depth increase along with theelevatio, poor rock integrity.(2) through the surface and adit deformation failure characteristics analysisshowed that atomization slope deformation and failure of both sides showed significant differences, on the right bank mainly slip-crack, slip-pressure-inducedfracturing, Sliding along the surface covering layers, on the left bank mainly underfalling failure by the effect of weathering and unloading. select control significance ofstructural plane potential unstable block, and use GeoStudio software which based onthe limit equilibrium method to quantitatively analysis the stability of natural slope.The results show that: in natural and storm condition,the slope is in the basic stabilityto stable state; in the seismic condition,the slope is in less stable to the basic steadystate, local slope is unstable; in storm and seismic conditions, the slope is in limitequilibrium-instability state.(3) Through the engineering analogy, predict bottom flow forecast flooddischarge atomization influence scope and rainfall intensity of Yagen II hydropowerstation, study groundwater permeability and stress distribution law by of SEEP andSIGMA/W module in GeoStudio software under various conditions. The results showthat: in the atomizing rainfall conditions, underground water level slope in the uplift isgreatly affected by the rainfall intensity and duration of rainfall influence, and areclosely related with soil properties of rock mass; Along the stilling pool wall and thefault zone there is shear stress concentration and shear strain during atomized rain,maximum shear stress and strain increase with the rainfall intensity and duration,stress concentration and strain associated with rainfall intensity.(4) on the basis of the seepage and stress research, quantitatively analysis thestability of the atomization slope under various conditions by limit equilibrium,analysis results show that: the stilling pool near the slope stability decrease sharply inhigh strength atomization under rainfall, complete loss of stability, covering layerstability is drastically reduced, while the stilling pool downstream to Ci marong brige,cashmere plot slope stability and natural state compared with no obvious decrease, butthe stability reduce in the natural rainfall and earthquake conditions, mostly ininstability-limit equilibrium state. Numerical results show that: under the atomizingrainfall condition, the stress distribution was changed greatly, the maximum,minimum principal stress is still compressive stress, increase with depth; But in theslope surface is tensile stress, and mainly focus on the influence of fault zone andstrong rainfall area, slope deformation intensifies, displacement variation is directlyrelated to rainfall intensity, the results consistent with limit equilibrium calculation.